Mohammad Wehbi

Liver-infiltrating lymphocytes in chronic human hepatitis C virus infection display an exhausted phenotype with high levels of PD-1 and low levels of CD127 expression.

ABSTRACT The majority of people infected with hepatitis C virus (HCV) fail to generate or maintain a T-cell response effective for viral clearance. Evidence from murine chronic viral infections shows that expression of the coinhibitory molecule PD-1 predicts CD8+ antiviral T-cell exhaustion and may contribute to inadequate pathogen control. To investigate whether human CD8+ T cells express PD-1 and demonstrate a dysfunctional phenotype during chronic HCV infection, peripheral and intrahepatic HCV-specific CD8+ T cells were examined. We found that in chronic HCV infection, peripheral HCV-specific T cells express high levels of PD-1 and that blockade of the PD-1/PD-L1 interaction led to an enhanced proliferative capacity. Importantly, intrahepatic HCV-specific T cells, in contrast to those in the periphery, express not only high levels of PD-1 but also decreased interleukin-7 receptor alpha (CD127), an exhausted phenotype that was HCV antigen specific and compartmentalized to the liver, the site of viral replication.

Impaired Hepatitis C Virus (HCV)-Specific Effector CD8+ T Cells Undergo Massive Apoptosis in the Peripheral Blood during Acute HCV Infection and in the Liver during the Chronic Phase of Infection

ABSTRACT A majority of patients infected with hepatitis C virus (HCV) do not sustain an effective T-cell response, and viremia persists. The mechanism leading to failure of the HCV-specific CD8+ T-cell response in patients developing chronic infection is unclear. We investigated apoptosis susceptibility of HCV-specific CD8+ T cells during the acute and chronic stages of infection. Although HCV-specific CD8+ T cells in the blood during the acute phase of infection and in the liver during the chronic phase were highly activated and expressed an effector phenotype, the majority was undergoing apoptosis. In contrast, peripheral blood HCV-specific CD8+ T cells during the chronic phase expressed a resting memory phenotype. Apoptosis susceptibility of HCV-specific CD8+ T cells was associated with very high levels of programmed death-1 (PD-1) and low CD127 expression and with significant functional T-cell deficits. Further evaluation of the “death phase” of HCV-specific CD8+ T cells during acute HCV infection showed that the majority of cells were dying by a process of cytokine withdrawal, mediated by activated caspase 9. Contraction during the acute phase occurred rapidly via this process despite the persistence of the virus. Remarkably, in the chronic phase of HCV infection, at the site of infection in the liver, a substantial frequency of caspase 9-mediated T-cell death was also present. This study highlights the importance of cytokine deprivation-mediated apoptosis with consequent down-modulation of the immune response to HCV during acute and chronic infections.

Genetic polymorphisms of human flavin monooxygenase 3 in sulindac-mediated primary chemoprevention of familial adenomatous polyposis.

Purpose: Sulindac is a nonsteroidal anti-inflammatory drug (NSAID) effective in regressing adenomas in patients with familial adenomatous polyposis (FAP). However, a recent randomized trial showed that sulindac, when compared with placebo, failed to prevent the development of adenomatous polyps in genotypically positive but phenotypically negative FAP patients. The present study determined whether polymorphisms in the gene encoding flavin monooxygenase 3 (FMO3), a hepatic microsomal enzyme that inactivates sulindac, played a role in determining the efficacy of sulindac in preventing polyposis in this cohort of FAP patients. Experimental Design: Genotyping was performed on seven established FMO3 polymorphisms previously shown to have functional relevance—M66I, P153L, E158K, V257M, E305X, E308G, and R492W—in 21 and 20 FAP patients, who received sulindac and placebo, respectively. Results: None of the 41 patients exhibited heterozygous or homozygous M66I and R492W variant alleles, or homozygous P153L, V257M, and E305X variant alleles. Among sulindac-treated patients who did not develop adenomas (“responders”), 4 (33%) were homozygous for E158K and 2 (17%) were homozygous for E308G variant alleles. In contrast, none of the patients on sulindac who developed adenomas (“nonresponders”) exhibited homozygosity for either of the two variant alleles. In addition, polymorphisms in the E158K or E308G allele were associated with a significant reduction in mucosal prostanoid levels in patients treated with sulindac. Conclusions: Polymorphisms in FMO3, particularly at the E158K and E308G loci, may reduce activity in catabolizing sulindac and result in an increased efficacy to prevent polyposis in FAP.

Genetic Polymorphisms of Flavin Monooxygenase 3 in Sulindac-Induced Regression of Colorectal Adenomas in Familial Adenomatous Polyposis

Sulindac is a nonsteroidal antiinflammatory drug with a chemopreventive effect in patients with familial adenomatous polyposis (FAP). In vivo, the active form of sulindac is sulindac sulfide, which is inactivated by the hepatic microsomal enzyme, flavin monooxygenase 3 (FMO3). In humans, numerous polymorphisms exist in FMO3, which alter enzymatic activity and subsequent substrate metabolism. We recently showed that certain polymorphic forms of FMO3 with reduced activity were associated with a more favorable response to sulindac in preventing the formation of adenomas in patients with FAP without polyps at baseline. Here, we determined whether these FMO3 polymorphisms correlated with the ability of sulindac to regress polyposis in patients with FAP who had polyps prior to treatment. Nineteen patients were treated with 150 mg sulindac twice a day for 6 months. The size and number of polyps in each patient was assessed at baseline (prior to the administration of sulindac), and at 3 and 6 months. Genotyping was done on seven established FMO3 polymorphisms with functional significance—M66I, E158K, P153L, V257M, E305X, E308G, and R492W. Statistical analyses were done with Wilcoxon rank sum test. Of the loci examined, only E158K and E308G showed polymorphic changes. Six patients exhibited polymorphisms in both E158K and E308G loci and were designated as genotype combination 1. The remaining patients were designated as genotype combination 2. Over the course of treatment, patients with genotype combination 1 had a greater reduction in both the size and number of polyps than those with genotype combination 2. These results suggest that combined polymorphic changes in the E158K and E308G alleles may protect against polyposis in patients with FAP treated with sulindac.

Carcinoid tumors: what should increase our suspicion?

Carcinoid tumors are neuroendocrine neoplasms, primarily of the gastrointestinal tract. Their incidence has been increasing over the last 2 to 3 decades. Patients often present with vague, nonspecific symptoms. Thus, primary care physicians should keep this diagnosis in mind and start appropriate diagnostic testing if they suspect it on a clinical basis. Patients with carcinoid tumors are also at increased risk of developing other malignancies, so close follow-up by their primary care physician is necessary. Patients often present with vague, nonspecific symptoms, and unless the primary care physician suspects that the patient has a carcinoid tumor, the appropriate testing is seldom ordered.

Pharmacogenetics and diseases of the colon

Purpose of review The deciphering of the human genome sequence has enabled the identification of genetic polymorphisms that are responsible for inter-individual variation in the response to drug therapy. This field is referred to as pharmacogenetics. We review the impact of pharmacogenetics on therapy in diseases of the colon using three common variant enzyme systems as examples. Recent findings Many enzyme systems impact the treatment of diseases of the colon. Examples include thiopurine S-methyltransferase, dihydropyrimidine dehydrogenase and flavin monooxygenase 3. They affect the management of inflammatory bowel disease, colorectal cancer and the chemoprevention of colorectal adenoma by influencing the metabolism of their respective substrates, azathioprine/6-mercaptopurine, 5-fluorouracil and sulindac. Recent studies have implicated the significance of genetic polymorphisms in each of the three drug-metabolizing enzymes, which impacts on the therapeutic outcome of the stated diseases. These studies highlight the potential role of pharmacogenetics in the design of a therapeutic plan which would increase efficacy and limit toxicity. Summary Pharmacogenetics of drug-metabolizing systems continues to gain significance in the drug therapy of a variety of disease states including those of the gastrointestinal tract.

A case of colitis cystica profunda in association with diverticulitis.

To the Editor: Colitis cystica profunda (CCP) is an uncommon benign lesion of the colon and rectum characterized by the presence of intramural mucous-containing cysts. It can mimic a malignant condition clinically and histologically.

Efficacy and safety of transjugular intrahepatic portosystemic shunt in the treatment of nongastric extraesophageal variceal bleeding.

Objectives: Although esophageal varices are the most common site of variceal bleeding, extraesophageal varices cause up to 30% of variceal bleeding. Unlike esophageal variceal bleeding, the experience in management of extraesophageal variceal bleeding, especially nongastric extraesophageal variceal bleeding is limited, and there are no established guidelines for treatment of nongastric extraesophageal variceal bleeding. This study aims to provide experience in treatment of nongastric extraesophageal variceal bleeding with transjugular intrahepatic portosystemic shunt in a tertiary medical center. Methods: We retrospectively reviewed all cases, admitted or transferred to Emory University Hospital, with extraesophageal variceal bleeding who had transjugular intrahepatic portosystemic shunt as the final resolution to control bleeding over a period of 4 years, from January 1999 to January 2003. We also compared the outcomes after transjugular intrahepatic portosystemic shunt for bleeding from gastric varices and nongastric extraesophageal varices. Results: Forty-one patients (33 gastric varices and 8 nongastric extraesophageal varices) with extraesophageal variceal bleeding who had transjugular intrahepatic portosystemic shunt performed were identified in this study period. Bleeding was controlled immediately in 90% (37/41) of those patients. The mortality was 7% (3/41). The rebleeding rate was 10% (4/41). Encephalopathy occurred in 24% (10/41) of the patients. Patients with gastric varices bleeding appeared to have more advanced liver disease than patients with nongastric extraesophageal varices bleeding. The outcomes after transjugular intrahepatic portosystemic shunt for bleeding from gastric varices and nongastric extraesophageal varices were similar. Conclusions: Transjugular intrahepatic portosystemic shunt is an effective and safe treatment of extraesophageal variceal bleeding, including bleeding from gastric varices and nongastric extraesophageal varices.

Nocturnal hydration--an effective modality to reduce recurrent abdominal pain and recurrent pancreatitis in patients with adult-onset cystic fibrosis.

Recurrent abdominal pain and recurrent pancreatitis are common problems associated with some patients with cystic fibrosis (CF). There is no known effective method to prevent recurrent abdominal pain and recurrent pancreatitis in such patients. The objective of this study was to determine whether nocturnal hydration (NH) prevents recurrent abdominal pain and recurrent acute pancreatitis in patients with adult-onset CF. Adult CF patients who were referred to our Pancreatic Diseases Clinic for recurrent abdominal pain and pancreatitis were enrolled in the study. Each patient was encouraged to drink plenty of water during the night and established a 6-month diary (3 months before and 3 months after NH was initiated), recording the frequency and severity of their abdominal pain, the amount of pain medication taken, and the volume of their water intake. We also reviewed the number of doctors clinic visits, emergency room visits, and hospitalizations for about 1 year before and 1 year after the initiation of the NH. The frequency and the severity of abdominal pain in this group of patients were significantly reduced. The amount of pain medication and the number of emergency room visits and hospitalizations for abdominal pain and acute pancreatitis were reduced. NH is a simple and cost-effective method to prevent recurrent abdominal pain and pancreatitis in patients with adult-onset CF.